ABSTRACT
Chalcogens include various chemical elements, among which are biologically active and important as selenium (Se), sulfur (S), and tellurium (Te). S is one of the essential macronutrients for plants, it is part of all proteins. Se is a microelement that is needed for the redox processes, synthesis of the necessary compounds, and stress resistance and response in plant and animal organisms. Te is always contained in trace amounts in most organisms, but its biological role has not been fully understood. To compensate for the lack of Se and S in the soil, but at the same time to avoid the negative effects associated with the possible toxicity of chalcogen compounds at the large concentration for plants and beneficial microorganisms; it is of interest to study their use in the form of nanoparticles (NPs) for plant treatment. In this chapter, various methods for the synthesis of Se, S, and Te NPs are considered in detail: physical, chemical, and also using different organisms like plants, bacteria, and fungi. The latter fungi-based synthesis method has gained popularity in recent years due to the discovery of a variety of enzymes that are involved in this process. The effect of NPs on plants depends on their size and concentration. Available studies indicate a positive effect of Se and S NPs on the viability of plants and their resistance to stress, in particular to biotic stresses. For example, S NPs were highly effective against the soft rot of ginger caused by the fungal pathogen Fusarium oxysporum and increased resistance of tomatoes to F. oxysporum f. sp. lycopersici. Nanosized Se obtained by laser ablation induced systemic resistance of tomatoes to the root-knot nematode Meloidogyne spp. Se NPs increased the resistance of tomatoes to late blight caused by the fungal pathogen Phytophthora infestans. The stimulating effect of NPs on plant immunity is associated with an increase in the intensity of photosynthesis, a change in the fatty acid profile of lipids, a decrease in the level of lipid peroxidation (LPO), an increase in the content of essential organic compounds in plant tissues, and an increase in the activity of antioxidant enzymes as a result of exposure to NPs.
